About ROT13 Encoder / Decoder
The ROT13 tool applies the ROT13 (Rotate-by-13) substitution cipher to any text. Each letter is replaced with the letter 13 positions after it in the alphabet. Since the alphabet has 26 letters, applying ROT13 twice returns the original text — encoding and decoding are the same operation.
ROT13 was widely used in Usenet newsgroups to hide spoilers, punchlines, and offensive content behind a simple encoding that required deliberate action to read. It is also used as a simple obfuscation for puzzles, games, and demonstrations.
Non-letter characters (numbers, spaces, punctuation) are preserved unchanged.
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How to Use ROT13 Encoder / Decoder
Enter your text.
The ROT13 result appears instantly. The same operation encodes and decodes.
Copy the result.
Examples
Frequently Asked Questions
Is ROT13 a secure cipher?
No — ROT13 is a trivial substitution cipher with zero cryptographic security. It is used only for obscuring text from casual view, not for protecting sensitive data.
Why is ROT13 its own inverse?
Because the alphabet has 26 letters and 13 + 13 = 26. Shifting by 13 twice returns to the original position, so one operation both encodes and decodes.
What is the difference between ROT13 and Caesar cipher?
Caesar cipher shifts letters by any amount (originally 3). ROT13 is a specific Caesar cipher with a shift of exactly 13. Caesar cipher requires knowing the shift amount to decode; ROT13 is always self-decoding.
Does it affect numbers and punctuation?
No — only letters (A–Z and a–z) are shifted. Numbers, spaces, and punctuation pass through unchanged.
What is ROT47?
ROT47 is a variant that shifts all printable ASCII characters (not just letters) by 47 positions within the printable ASCII range (33–126).